Providing both multimedia (voice, video and data) communication products and services to customers is playing an increasingly important role for telecommunications companies today. The power of multimedia communications is evident from the expansion in "videoconferencing", in which a user at a videoconferencing station can communicate "face-to-face" in real time with persons at other videoconferencing stations. The introduction of desktop videoconferencing equipment is making multimedia communications even more prevalent. Generally, multimedia communications uses equipment incorporated as part of a general purpose computer, or integrated systems specifically designed for the task. Various multimedia products are available that enable users to exchange audio, video, and data through their PCs with one another by communicating over ISDN phone lines or over switched 56 kbps phone lines. An MS-Windows.TM.-based teleconferencing application enables a user to place a multimedia phone call to one or a plurality of other similarly equipped PCs through a bridge known as a Multimedia Control Unit (MCU). The interconnected users are then able to engage in a video teleconference phone call with the camera input of one user appearing in a window on the PC of all the other users. The image of the particular participant that is displayed in the window on each user's PC will generally change in accordance with the dynamics of the conference such as selecting for display to all the participants, the video input from the one participant whose audio signal is loudest. In addition to the exchange of audio and video, data can also be shared between the users either by the exchange of files or through the use of shared applications running simultaneously on the connected PCs. Thus, for example, a document originating at one user's terminal can be displayed on another window on each of the other users' terminals.
Generally the multimedia equipment used for such teleconferencing conforms to the H.320 protocol that has been adopted by the International Telecommunications Union (ITU) as an international standard for videoconferencing. The H.320 standard is a family of videoconferencing standards developed and maintained by the ITU which encompasses a variety of standards for audio compression, video compression, and telephone call set-up and control. The H.320 standard provides for the division of information into three distinct streams: video, audio, and data, where "data" herein is intended to mean digital information that is not meant to be displayed as real-time video or audio, and includes information to be displayed as text, such as documents, and data that is used to control applications or convey status to them. A PC operating in accordance with the H.320 standard is thus constrained to communicate only with one or more similar devices operating under the same standard.
In order to allow a Plain Old Telephone Service (POTS) end-user who does not have an H.320 compatible terminal to participate, albeit in a limited fashion, in a videoconference with users having H.320 compatible terminals, an audio port is connected to an MCU configured in accordance with the H.320 standards. An end-user, connected to the audio port over a POTS connection, is then able to participate in the audio portion of the conference call, by listening to the audio portion of the ongoing conference and providing audio input to the conference. Of course, without the multimedia capabilities of an H.320 compatible terminal, the functionality of a voice-only endpoint is severely limited, since neither data in the form of documents can be received, nor can video images from any of the other participants. This in turn limits the functionality available to the users at the multimedia endpoints who in turn can neither see the voice-only caller, nor receive or send data in the form of documents that might need to be shared with the user at the voice-only endpoint.
An object of the present invention is to provide a system and a method for expanding the functionality of an analog voice-only non-H.320 compatible endpoint.